CERN’s systems have unique requirements in terms of scale, synchronisation and geographic distribution. As a result, a lot of their hardware is produced to bespoke specifications.

Serrano spoke about the models available when considering closed/open and commercial/non-commercial licensing. Due to the long lifespan and iterative nature of CERN’s systems, a commercial proprietary solution would create vendor lock-in which isn’t acceptable for their requirements. An open solution without commercialisation wouldn’t be sustainable. He concluded that an open, commercialised solution provides “the best of both worlds” in terms of sustainable support and sharing of knowledge, which is one of CERN’s core goals.

The licence itself takes inspiration from the GNU GPL for software, with modifications to make it more applicable to hardware. The licence is designed to cover the documentation for the hardware (such as CAD files and bills of materials), allowing the documents to be distributed, modified, and used to manufacture products given that the documentation is made accessible to those receiving the products.

Serrano described the licence as “weak-copyleft”. It is designed to ensure that modifications to the design, used complete or in part, are shared back to the community. However, it does not attempt to stipulate that the designs of other products that are integrated or linked with the OHL products also have their designs shared.

Similarly, the licence contains a patent grant to any patents owned by the designer, but it doesn’t attempt to make this reciprocal – the licensee isn’t required to license their own patents back to the licensor.

A final notable feature of the licence is the stipulation that alongside any trademarks and copyright notices, any references to the location of the documentation must not be removed from the designs. This means, for example, that a URL to access the documentation could be included in the top copper layer of a PCB – this would ensure than anyone receiving the board would have access to the designs.

Serrano finished by introducing White Rabbit – a network time protocol which improves on the Precise Time Protocol standard to synchronise networked nodes with tolerance of under a nanosecond. The documentation for the hardware implementing White Rabbit is released under the CERN OHL.

A big thanks to Oxhack for hosting the event, and Moorcrofts for sponsoring it.